Impact of tops and green leaves on sugarcane processing: laboratory testing

Abstract

In Réunion, changes in harvesting practices have led to increased amounts of sugarcane tops and leaves delivered to factories. To anticipate the changes in sugar recovery processing, laboratory trials were undertaken. Samples with known quantities of tops or green leaves were prepared and cane processing was simulated at laboratory scale: juice extraction, clarification and evaporation with operating parameters similar to those in the factory. Juice and syrup were collected and analyzed for sugar quality parameters, as well as parameters that impact sugar recovery or processing quality: ash and reducing sugars contents were monitored to estimate the sucrose loss to molasses, while calcium, phosphate and oxalate contents were monitored to evaluate the risk of fouling in evaporator. Results highlight a degradation of juice composition with increasing quantities of tops and leaves, an increase in lime consumption, and color. An increase in residual calcium in syrup was observed thus increasing the risk of evaporator fouling. The mixed juice, clear juice and syrup qualities declined in the same proportion and the composition of the juice did not get worse with juice treatment.